The LensCoat®Extender set includes a cover for the Canon 1.4 and 2.x extenders. Two small holes line up with the red dot indicator, making it easy to quickly line up your extender with camera mount and lens with the cover installed as well as a hole for the extender release.

Concur with Bruce Dickson: the holes for the red alignment dots are too small. This leads to an occasional, and irritating, user experience where you are looking for the dot when attaching lenses or bodies...